Aluminum coil: lightweight, continuously manufactured green metal coil

In modern industrial, large-scale, automated production lines, aluminum coil, with its core advantages of lightweight aluminum and continuous coil feeding, has become a key link between aluminum processing and downstream manufacturing. Made from pure aluminum or aluminum alloys, it is directly coiled after hot or cold rolling. While inheriting aluminum's core properties of low density (2.7g/cm³, only one-third that of steel), natural corrosion resistance, high thermal and electrical conductivity, and ease of processing, its coiled form adapts to automated processes such as continuous stamping, rolling, and coating. It is widely used in architectural decoration, transportation, electronic packaging, and new energy, making it a core and foundational coil material in the trend toward lightweight manufacturing and efficient production.

I. Basic Concepts and Core Composition of Aluminum Coil

The core composition of aluminum coil is the same as that of aluminum sheet, consisting of pure aluminum (Al) or aluminum alloys (with added elements such as Mg, Si, Mn, and Zn), with an aluminum content of ≥95% (≥99% for pure aluminum coil). The key difference lies in the **"coil shape and production logic": after rolling, no single sheet cutting is performed, and the coiler is used to roll it into a cylindrical coil to meet the needs of downstream continuous processing. (I) Material Basics: Core Differences Between Pure Aluminum Coil and Aluminum Alloy Coil
Pure Aluminum Coil: Aluminum purity ≥ 99.0% (e.g., 1050 and 1060 coils), free of alloying elements, offers excellent electrical and thermal conductivity (pure aluminum coil thermal conductivity 237W/(m・K)), strong corrosion resistance, but low strength (tensile strength 90-120MPa). Suitable for continuous production applications with high functionality and low strength requirements (e.g., packaging foil, conductive tape).
Aluminum Alloy Coil: Optimized by the addition of alloying elements, these coils are classified similarly to aluminum sheet, but emphasize "coil rolling stability" (to prevent cracking and deviation during coiling).
3-Series Aluminum-Manganese Coil (containing 1.0%-1.5% Mn): Better corrosion resistance than pure aluminum coil, with medium strength (180-250MPa), suitable for continuous outdoor production (e.g., architectural decorative panels).
5-Series Aluminum-Magnesium Coil (containing 1.0%-5.0% Mg: Excellent weather resistance (especially seawater resistance), high strength (200-350 MPa), suitable for continuous processing in the marine and transportation sectors (such as RV hulls);
6-series aluminum magnesium silicon coil (containing 0.4%-1.0% Si+Mg): Heat-treatable (T6 temper) strengthening, high strength (250-400 MPa), and easy processing make it the mainstay of general-purpose structural aluminum coil (such as automotive battery housings);
7-series aluminum zinc magnesium coil (containing 5.0%-7.0% Zn+Mg): Ultra-high strength (500-700 MPa), but weak corrosion resistance, making it suitable only for high-end continuous structural parts (such as aviation components). (II) Manufacturing Process and Morphological Characteristics
The aluminum coil manufacturing process is "aluminum ingot smelting → casting and rolling into billets → hot rolling/cold rolling → coiling → surface treatment." Key process features include:
Hot-rolled aluminum coil: The aluminum billet is heated to 400-500°C (below the aluminum melting point of 660°C) and rolled. The thickness is 2-10mm, and the coil weight is 10-30 tons. It has an oxide scale on the surface (requiring pickling) and good toughness, making it suitable for continuous forming of thick-walled structural parts (such as mold base plates and chemical equipment).
Cold-rolled aluminum coil: Using hot-rolled coil as raw material, it is rolled in multiple passes at room temperature. The thickness is 0.1-2mm, and the coil weight is 5-25 tons. It has a smooth surface (roughness Ra ≤ 0.8μm) and high dimensional accuracy (thickness tolerance ±0.01mm), making it suitable for precision continuous processing (such as home appliance panels and electronic housings).
Advantages of coil form: Single coil lengths can reach 500-2000 meters (e.g., a 0.5mm thick cold-rolled coil is approximately 1000 meters long). 2500 meters), continuous feeding via an automated uncoiler eliminates the efficiency loss of frequent reloading of single sheets.

Common aluminum coil specifications: thickness 0.1-10mm (mainstream 0.3-2mm), width 1000-2000mm (customizable extra-wide coils exceeding 3000mm), coil weight 5-30 tons (standard 20 tons, compatible with mainstream production line loads), inner diameter 508mm or 610mm (standard core, compatible with uncoilers).
II. Core Classification of Aluminum Coil (By Material and Process)
The classification logic for aluminum coils revolves around "material performance" and "suitability for continuous processing." Different classifications correspond to specific application scenarios, ensuring efficient matching with downstream demand:

(I) Classification by Material (Alloy Series) (Core Dimension)
Series 1 Pure Aluminum Coil (approximately 20%)
Features: High purity (99.0%-99.9%), excellent electrical and thermal conductivity, strong corrosion resistance, low strength, coil weight of 5-15 tons (primarily thin gauge), suitable for low-speed continuous processing (such as aluminum foil rolling).
Applications:
Packaging: 1060 pure aluminum coils (0.1-0.3mm) are continuously rolled into food packaging aluminum foil (0.005-0.02mm) and can substrates (0.2-0.3mm).
Conductive: 1050 pure aluminum coils (0.5-1.0mm) are continuously cut into transformer busbars and wire and cable cores (conductivity 62% IACS).
3-series aluminum-manganese alloy coils (approximately 15%)
Features: Contains Mn, resulting in better corrosion resistance than pure aluminum coils. Medium strength, coil weights of 10-20 tons, and easy surface treatment (painting and brushing possible), making it suitable for outdoor continuous forming.
Applications:
Architectural Decoration: 3003 aluminum coil (0.3-0.8mm) is continuously sprayed to produce color-coated aluminum coil for factory wall panels and advertising signs.
Home Appliance Components: 3003 aluminum coil (0.4-0.6mm) is continuously stamped to produce air conditioner radiators and refrigerator evaporators (heat conductive and corrosion resistant).
5 Series Aluminum-Magnesium Alloy Coil (approximately 25%)
Features: Contains magnesium, offers excellent weather resistance (salt spray corrosion resistance for over 5,000 hours), high strength, and coil weights of 15-25 tons, making it suitable for continuous processing in harsh environments.
Applications:
Marine Engineering: 5052 aluminum coil (0.8-2.0mm) is continuously welded to produce ship decks and offshore platform treads.
Transportation: 5083 aluminum coil (1.5-3.0mm) is continuously rolled to produce RV hulls and high-speed rail carriage side panels (lightweight and weather resistant). 6 Series Aluminum-Magnesium-Silicon Alloy Coil (approximately 30%)
Features: Heat-treatable, high-strength, and easy to process (bending radius ≤ 2 times thickness). With a coil weight of 10-30 tons, it offers the best value for money and is the primary choice for general-purpose structural aluminum coil.
Applications:
New Energy Vehicles: 6061 aluminum coil (1.0-3.0mm) is continuously stamped into battery cases and vehicle body frames (reducing weight by 40%);
Electronic Equipment: 6063 aluminum coil (0.3-0.8mm) is continuously cut into laptop cases and mobile phone mid-frames (lightweight and strong);
Architectural Structures: 6061 aluminum coil (2.0-5.0mm) is continuously formed into aluminum alloy scaffolding and curtain wall studs. 7 Series Aluminum-Zinc-Magnesium Alloy Coil (approximately 5%)
Features: Contains Zn and Mg elements, offers ultra-high strength (T6 tensile strength ≥500 MPa), coil weight of 10-15 tons (to avoid damage to the production line due to excessive weight), and requires surface treatment (anodizing, painting) to enhance corrosion resistance.
Applications:
Aerospace: Continuously processed 7075 aluminum coil (2.0-5.0 mm) into aircraft fuselage skins and drone frames;
High-end molds: Continuously cut 7050 aluminum coil (5.0-10 mm) into precision stamping die bases (hardness HB150-180). (II) Classification by Rolling Process and Surface Treatment

By Rolling Process

Hot-rolled aluminum coil: 2-10mm thickness, 20-30 tons coil weight, rough surface (Ra ≤ 6.3μm), good toughness, suitable for thick-walled continuous structures (such as chemical storage tank cylinders and large molds);

Cold-rolled aluminum coil: 0.1-2mm thickness, 5-25 tons coil weight, smooth surface (Ra ≤ 0.8μm), high precision, suitable for precision continuous processing (such as electronic components and decorative parts).

By Surface Treatment (Derived Coil)

Anodized Aluminum Coil: Cold-rolled coil undergoes continuous electrolysis to form a thick oxide film (50-200nm). It can be dyed (gold, black) and is used for high-end decoration (hotel walls, furniture handles).

Pre-Coated Aluminum Coil: Cold-rolled coil is continuously spray-coated with fluorocarbon paint or polyester paint, offering 15-20 years of weather resistance. It is used for building curtain walls and integrated housing wall panels.

Brushed Aluminum Coil: Cold-rolled coil is continuously brushed (straight or random graining) to provide fingerprint resistance. It is used for electronic device casings and home appliance panels.

Laminated Aluminum Coil: Cold-rolled coil is coated with PVC film to provide scratch resistance. It is used for furniture panels and interior decoration.

III. Key Performance Advantages of Aluminum Coil (Comparison of Aluminum Sheet and Steel Coil)

The performance advantages of aluminum coils are a combination of aluminum's material properties and continuous coil processing, precisely addressing the pain points of large-scale production:

Continuous Processing Efficiency: From "Single-Sheet Loading" to "Unmanned Feeding"

Aluminum sheets require manual loading of individual sheets (daily processing capacity ≤ 1,000 m2), while steel coils, due to their weight (a steel coil of the same specification weighs three times as much as an aluminum coil), require heavy equipment to handle. Aluminum coils can be continuously fed through automated uncoilers (at speeds of 10-20 m/min, with a daily production capacity of ≥ 12,000 m2), making them suitable for continuous production lines such as stamping, welding, and coating. For example, new energy vehicle manufacturers use 6-series aluminum coils to produce battery casings, achieving a daily production capacity of 20,000 units, 2.5 times that of aluminum sheet. Lightweight + Low Energy Consumption: Reduced Manufacturing and Use Costs

Aluminum coils have a density of only 2.7g/cm³, and weigh 34% less than steel coils of the same specification (for example, a 1000-meter-long, 0.5mm-thick aluminum coil weighs approximately 1.35 tons, while a steel coil weighs 4 tons). Handling energy consumption is reduced by 66%. During downstream processing, stamping aluminum coils consume only 50% of the energy of steel coils (due to aluminum's lower hardness (HB25-35 vs. HB130-180 for steel). Finished products are also 30%-70% lighter (for example, aluminum coils used in automobile bodies reduce fuel consumption by 1.5-2L/100km). Material Utilization: From "Scrap" to "Zero Waste in Fixed Lengths"

When cutting aluminum sheets, the scrap rate is ≥10% (e.g., a 1.2m-wide wall panel requires cutting into 1.5m-wide sheets). Aluminum coils can be customized to the width of downstream products (e.g., a 1.2m-wide wall panel requires a 1.2m-wide coil). Material utilization is ≥98%, and continuous processing eliminates seams (e.g., wall panels formed from color-coated aluminum coils for construction are more water-resistant than spliced ​​aluminum sheets). Corrosion Resistance + Low Maintenance: Lifecycle Cost Advantages

Aluminum coils naturally form an Al₂O₃ oxide film on their surface (resisting a room-temperature corrosion rate of 0.0001mm/year), requiring no paint or maintenance (steel coils require regular painting, with an average annual maintenance cost of 15 yuan/㎡). 5-series aluminum-magnesium coils are 50 times more corrosion-resistant than steel coils in seawater, and their 20-year lifecycle cost is only one-third that of steel coils (for example, 5052 aluminum coils used on offshore platforms have no maintenance costs).
IV. Key Application Areas of Aluminum Coil (Large-Scale Continuous Manufacturing Scenarios)
Aluminum coil's lightweight and continuous processing characteristics make it a dominant player in mass production applications. Key applications are as follows:
(I) Construction (approximately 30%)
Building Decoration and Enclosures:
Color-coated aluminum coils (3/5 series, 0.3-0.8mm) are continuously formed into factory wall and roof panels (daily production capacity: 10,000 square meters), offering 15-20 years of weather resistance. For example, large industrial parks use 3003 color-coated aluminum coils, with a single roll covering a 1,000 square meter roof.
Anodized aluminum coils (6 series, 0.5-1.0mm) are continuously cut into hotel curtain walls and elevator panels (both aesthetically pleasing and corrosion-resistant). For example, high-end shopping malls use 6063 anodized aluminum coils, dyed in a champagne gold, with no risk of fading. Structural Parts:
6 Series aluminum coils (2.0-5.0mm) are continuously formed into aluminum alloy scaffolding and curtain wall keels (lightweight, 50% increase in installation efficiency). For example, 6061 aluminum coils are used in high-rise building curtain walls, with a single coil producing 200 keels, resulting in a 40% weight reduction.
(II) Transportation (approximately 25%)
New Energy Vehicles:
6061 aluminum coils (1.0-3.0mm) are continuously stamped into battery casings (daily production capacity of 20,000 pieces) and body panels (doors, hoods). For example, the BYD Han uses 6 Series aluminum coils, resulting in a 35% weight reduction and a 100km increase in range.
5052 aluminum coils (2.0-4.0mm) are continuously welded into chassis components (corrosion-resistant), replacing steel coils for a 60% weight reduction. Aerospace and Rail Transit: 7075 aluminum coils (2.0-5.0mm) are continuously processed into aircraft fuselage skins and drone frames (ultra-high strength and lightweight); 5083 aluminum coils (1.5-3.0mm) are continuously rolled into high-speed rail car side panels and subway air conditioner casings (weather-resistant and weight-reduced). (III) Electronics and Packaging (approximately 25%) Electronics and Electrical Appliances: 6-series aluminum coils (0.3-0.8mm) are continuously stamped into laptop casings (daily production capacity of 15,000 pieces) and mobile phone mid-frames (lightweight and strong); 1-series pure aluminum coils (0.1-0.3mm) are continuously cut into LED heat sinks and power bank casings (with a thermal conductivity five times that of steel coils). Packaging:
1060 pure aluminum coils (0.1-0.3mm) are continuously rolled into food packaging aluminum foil (0.005-0.02mm, daily production capacity: 500 tons) and can base sheets (0.2-0.3mm, daily production capacity: 1 million sheets);
3003 aluminum coils (0.2-0.4mm) are continuously formed into aluminum-plastic panels for pharmaceutical packaging (corrosion-resistant and free of heavy metal leaching).
(IV) New Energy and Industrial Sector (approximately 20%)
New Energy:
6 Series aluminum coils (0.1-0.3mm) are continuously cut into photovoltaic module backsheets (lightweight and weather-resistant), with a daily production capacity of 10,000 sheets;
1 Series pure aluminum coils (0.5-1.0mm) are continuously processed into conductive components for hydrogen energy equipment (conductive and resistant to hydrogen embrittlement).​
Industrial: ​
6-series aluminum coils (5.0-10mm) are continuously cut into precision mold bases (such as stamping dies, hardness HB120-150); ​
5-series aluminum coils (5.0-20mm) are continuously welded into chemical storage tank cylinders (corrosion-resistant, replacing stainless steel coils at a 50% cost reduction).
V. Future Development Trends of Aluminum Coil

With the advancement of the "dual carbon" goals and the upgrading of high-end manufacturing, aluminum coil is developing towards "high strength, ultra-thinness, ultra-wideness, multifunctionality, and greenness":

High Strength: Breaking Through Structural Application Limitations

Developing "ultra-high-strength aluminum alloy coils," such as 7-series aluminum-zinc-magnesium-copper coils (tensile strength ≥800 MPa), approaching high-strength steel coils for use in heavy-duty truck frames (reducing weight by 50%) and large passenger aircraft fuselages; improving the strength of 5-series and 6-series aluminum coils through microalloying (adding scandium and zirconium), such as 5052 modified coils with strength increased to 400 MPa, replacing more steel coil applications.

Ultra-thinness and Ultra-wideness: Suitable for Precision and Large-Scale Applications

Developing breakthroughs in "ultra-thin aluminum coil" manufacturing technology, such as 0.05mm thick pure aluminum coils (only half the diameter of a human hair), for use in flexible electronic display substrates and lithium battery separators; developing ultra-wide cold-rolled aluminum coils over 3000mm.

Rolls are used for large-scale building curtain walls (a single sheet covers 6 square meters, reducing seams) and high-speed rail carriage side panels (formed in one go, increasing efficiency by 30%).

Functional Composites: Expanding Multi-Scenario Needs

Developing "multifunctional composite aluminum rolls": such as "thermal conductive + insulating" composite rolls (with a ceramic film on the surface, used in electronic heat sinks), "antibacterial + corrosion-resistant" rolls (with silver ion additions, used in medical device casings), and "self-healing" rolls (which automatically repair damaged oxide films for long-term outdoor use). We are also promoting the composites of aluminum rolls with other materials (aluminum-steel composite rolls, aluminum-carbon fiber composite rolls), achieving both lightweight and high strength. Greening: Carbon Reduction and Circular Upgrading
Promote "Green Aluminum Coil" production: Use photovoltaic/wind power electrolytic aluminum (90% lower carbon emissions than thermal power), aiming for recycled aluminum coil to account for 50% of the total by 2030 (currently 30%); establish a closed-loop system of "aluminum coil - scrap aluminum coil - recycled aluminum coil," with recycled aluminum coil consuming only 5% of the energy of virgin aluminum coil and achieving performance close to virgin aluminum (purity ≥ 99.5%); develop environmentally friendly surface treatment technologies such as chromium-free passivation and water-based spray coating to reduce heavy metal pollution.

Conclusion
Aluminum coil, combining the lightweight advantages of aluminum with the efficiency of continuous coil processing, addresses the pain points of aluminum sheet (low single-sheet processing efficiency and high waste) while also addressing the limitations of steel coil (heavy weight, high energy consumption, and poor corrosion resistance), becoming an efficiency engine for large-scale high-end manufacturing. From mass-produced battery casings for new energy vehicles to continuously formed wall panels for building curtain walls, from aluminum foil coils for food packaging to high-strength structural components for aerospace, aluminum coils are present throughout the entire supply chain: consumer goods, high-end manufacturing, and environmental protection. In the future, with breakthroughs in high-strength alloy research and development and green processes, aluminum coils will further replace steel coils, becoming the core foundational coil supporting the "dual carbon" goals and the upgrade of high-end manufacturing.